1. Field of the Invention
The present invention relates to a radio selective calling receiver, and particularly to a radio selective calling receiver requiring input of a password in order to protect confidentality when using key input to operate the radio selective calling receiver.
2. Description of the Related Art
As shown in FIG. 1, a radio selective calling receiver of the prior art is made up of antenna 11 that receives radio waves from a base station, radio unit 12 that demodulates a radio frequency signal outputted from antenna 11 and outputs digital signals received from the base station, switching unit 13 for inputting data and commands for controlling the operation of the radio selective calling receiver which is provided with a plurality of switches for input of commands and data, display 14 for displaying information relating to the input of commands and data from switching unit 13 and information relating to the operating state of the radio selective calling receiver, speaker 15 for sounding an alarm to inform a user of the reception of an incoming call from a base station, memory for storing, for example, data inputted by a subscriber or received data from a base station, and control unit 1b for controlling the operation of each of the above-described components.
Radio waves transmitted to a subscriber carrying the radio selective calling receiver are received at antenna 11. These radio waves, which include a call signal and transmitted data from the base station, are modulated, and the call signal and transmitted data are demodulated and extracted at radio unit 12 and outputted to control unit 1b. In accordance with the call signal, control unit 1b displays a message on display 14 to indicate that a call has come in and sends a ringing signal to speaker 15. In addition, control unit 1b both stores the transmitted data that has been received from the base station to memory 16 and indicates the data on the display.
For received data requiring confidentiality, a step is performed whenever required at both the transmitting and receiving side to place a restriction on operation of the radio selective calling receiver, thereby preventing access to received data by a third party so as to maintain the confidentiality of received data handled by the radio selective calling receiver.
Japanese Patent Laid-open No. 219034/87 describes one example of the prior art in which input of a password is employed to maintain confidentiality. According to the prior art described in this document, a plurality of packages mounted in a device are interconnected by means of connectors; and when trouble occurs in which connectors experience temporary states of poor contact followed by automatic restoration of contact while the device is operating, the functioning of the device is temporarily degraded or halted and then returns to full operation. The effect of these interruptions appears in the data being handled, impedes reliability of the system, and reduces the protection of confidentiality. To prevent these problems, input of a password is therefore required to initiate a return to the operating state of the device.
No measures have been available for protection from access by a third party of highly confidential information including sensitive information such as highly confidential telephone numbers stored in the memory of a radio selective calling receiver by the user of the radio selective calling receiver, and extreme care has therefore been required with regard to the handling of a radio selective calling receiver containing data requiring high confidentiality.
In the above-described radio selective calling receiver of the prior art, manipulation of the operation switches results in immediate operation of the functions of the radio selective calling receiver that correspond to the manipulated switches. As a consequence, if the radio selective calling receiver is being used for communication of a confidential item, careless handling of the radio selective calling receiver, such as leaving the radio selective calling receiver unattended on a desk, may result in the breach of confidentiality through manipulation by a third party. In other words, great care must be taken in handling the radio selective calling receiver in order to prevent disclosure to a third party of confidential information such as a telephone number that has been previously stored in the memory of the radio selective calling receiver, and this necessary extra care is a major disadvantage of the prior art.
In addition, despite measures taken on the transmitting side to maintain confidentiality of a sent message, failure to take corresponding measures on the receiving side may still allow a third party to access the radio selective calling receiver and read the received message. This added danger of breached confidentially underscores the need for extreme care and the resulting inconvenience of using the radio selective calling receiver of the prior art.